JP7565713B2 - Tube with insertion port and method for manufacturing tube with insertion port - Google Patents

Description

This invention relates to a tube having an insertion port and a method for manufacturing a tube having an insertion port.

Conventionally, there are pipes used to transport various fluids, and their joints have an expansion and contraction function and a separation prevention function. This type of joint structure is also called an earthquake-resistant pipe joint. For example, as shown in FIG. 5, a protrusion 10 provided on the outer periphery of the insertion port 1 of a pipe P engages with a lock ring 4 fitted into the inner peripheral groove of the receiving port 2 of another opposing pipe P to exert a separation prevention function. In addition, the protrusion 10 of the insertion port 1 moves a predetermined distance (corresponding to sections A and B in the figure) between the inner back end surface 3 of the receiving port 2 and the lock ring 4, allowing expansion and contraction in the pipe axial direction. In addition, a rubber ring 5 is provided between the insertion port 1 and the receiving port 2, ensuring liquid-tightness between the outer surface 1a of the insertion port 1 and the inner surface 2a of the receiving port 2. For example, a pipe P having an insertion port 1 is described in Patent Document 1.

The projection on the outer periphery of the insertion port is generally formed by fitting a metal ring around the outer periphery of the tube and then fixing the ring to the outer surface of the tube by welding or the like. For example, Patent Document 2 describes a method of forming the projection on the insertion port by welding a ring to the outer surface of the tube. In addition, for example, Patent Document 3 describes a method of forming the projection on the insertion port by depositing weld metal.

JP 2012-77788 A Japanese Patent Application Publication No. 9-122910 Patent No. 6082087

However, the method of forming the protrusion by welding the ring, as in Patent Document 2, has the problem that fitting the ring is time-consuming and requires a lot of time for the welding work and the processing before and after the welding. Also, the method of forming the protrusion by depositing weld metal, as in Patent Document 3, has the problem that the welding takes time because of the large amount of welded beads. Also, with methods that involve welding, it is difficult to maintain the quality of the welded area, and poor construction can cause excessive penetration into the base material, the tube, wasting material and making the tube more susceptible to breakage.

Therefore, the objective of this invention is to easily and accurately form the protrusion on the outer periphery of the insertion port by welding.

In order to solve the above problems, this invention employs a method for manufacturing a tube having a protrusion that protrudes radially outward from an insertion port at one end in the tube axial direction, in which a first welding material and a second welding material are used, an arc is generated by passing an electric current through the first welding material to form a molten part on the outer surface of the insertion port, and before the molten part hardens, the second welding material is applied to the molten part without passing an electric current through it, thereby forming the protrusion by weld build-up.

In this case, a configuration can be adopted in which the penetration portion where the weld metal of the first welding material and the second welding material fuses with the base material of the insertion port is formed to a depth from the outer surface of the insertion port that is 10% or more and less than 80% of the thickness of the base material of the insertion port.

In order to solve the above problems, the present invention employs a tube body having a protrusion that protrudes radially outward from an insertion port at one end in the tube axial direction, the protrusion being made of weld metal and protruding radially outward beyond the outer surface of the insertion port, and a fusion portion located on the inner diameter side of the protrusion and in which the base material of the insertion port and the weld metal are fused, the fusion portion extending from the outer surface of the insertion port to a depth of 10% or more but less than 80% of the thickness of the base material of the insertion port.

This invention allows the protrusions on the outer periphery of the insertion port to be formed easily and precisely by welding.

FIG. 1 is a cross-sectional view showing an embodiment of the present invention. Cross-sectional view showing the relative positions of the base material and the welding equipment during welding FIG. 1 is a perspective view showing the positional relationship between the base material and the welding device during welding. FIG. 2 is a cross-sectional view showing a modification of FIG. 1; Vertical cross section of joint

One embodiment of the present invention will be described with reference to Figures 1 to 4. This embodiment is a tube P having a protrusion 10 that protrudes radially outward from an insertion port 1 at one end in the tube axial direction, and a manufacturing method for the tube P. The main configuration of the tube P is as shown in Figure 5 used in the explanation of the conventional example, so its explanation will be omitted. Below, the explanation will focus on the configuration of the protrusion 10 of the insertion port 1, which is a feature of this invention.

The pipe body P has an insertion port 1 at one end in the pipe axis direction and a receiving port 2 at the other end in the pipe axis direction, and the insertion port 1 has a protrusion 10 that protrudes radially outward from the outer surface 1a of the insertion port 1 continuously around the entire circumference of the pipe axis (see Figure 5). This protrusion 10 is composed of a weld buildup formed from weld metal. In other words, a weld buildup (weld bead) is formed on the metallic base material that constitutes the insertion port 1, and the portion formed by the weld metal is the protrusion 10. Here, although it is said that the protrusion 10 is composed of the weld metal, this does not exclude the possibility that the material that constitutes the protrusion 10 includes the base material of the insertion port 1 melted into the weld metal.

As shown in Figures 1 and 4, the inner diameter side of the protrusion 10 has a penetration portion 11 that penetrates to a depth t1 on the inner diameter side of the outer surface 1a of the insertion port 1 and fuses the base material of the insertion port 1 with the weld metal. The maximum depth t1 of the penetration portion 11 is 10% to 80% of the thickness t0 of the base material of the insertion port 1 from the outer surface 1a of the insertion port 1.

The tube P before the protrusion 10 of the insertion port 1 is formed is manufactured by centrifugal casting. In centrifugal casting, a cylindrical mold is placed on rollers that rotate by a driving force, and while rotating the mold around its axis, molten metal is poured into the mold and the molten metal is hardened to form the tube P. The mold is provided with a dam to prevent the poured molten metal from leaking out. After hardening, the tube P is pulled out of the mold. The material of the tube P is adjusted by a specified heat treatment, etc., and then the protrusion 10 of the insertion port 1 is processed.

The welding device 20 for processing the protrusion 10 is shown in Figs. 2 and 3. This welding device 20 is a device for performing cold tandem welding, and is equipped with an arc welding torch 23 that supplies a first welding material 21 for arc welding in an energized state, and a welding material supply device 24 that supplies a second welding material 22 in a non-energized state. The arc welding torch 23 and the welding material supply device 24 are connected by a connecting member 25 and maintained at a predetermined distance. This predetermined distance can also be increased or decreased by adjustment.

The arc welding torch 23 uses a delivery device 28 to deliver the first welding material 21 to a welding position a on the outer surface 1a of the insertion port 1, which is the base material. The first welding material 21 functions as an electrode that passes a current, and an arc is generated between the base material and the first welding material 21 when a welding current supplied from a power source 27 is passed through the first welding material 21. As the first welding material 21, a well-known welding wire, for example, FeNi φ0.8 to 1.6 mm, can be used. In addition, as the first welding material 21, various materials such as well-known solid wire, flux wire, various welding rods, and strip electrodes can be used. In this embodiment, a welding wire is used as the first welding material 21, and will be referred to as the first welding wire 21 below.

The welding material supply device 24 uses the delivery device 26 to deliver the second welding material 22 toward the welding position b on the outer surface of the insertion port 1, which is the base material, without passing current through it. For example, FeNi φ0.8 to 1.6 mm can be used as the second welding material 22. In addition, various materials can be used as the second welding material 22, such as well-known solid wire, flux wire, various welding rods, and strip electrodes. In this embodiment, a welding wire is used as the second welding material 22, and will be referred to as the second welding wire 22 below.

Next, we will explain the manufacturing method of the tube body P according to this embodiment, in particular the method of forming the protrusion 10 of the insertion port 1.

3, the tube P is held by a gripping device H and can rotate around the tube axis as shown by the arrow R in the figure. This rotation of the tube P causes the arc welding torch 23 and the welding material supply device 24, which are connected by a connecting member 25, to move along the tube circumference relative to the insertion port 1 of the tube P, which is the base material. During this relative movement, it is desirable for the welding material supply device 24 to be positioned forward of the arc welding torch 23 along the rotation direction R of the tube P. In other words, it is desirable for the position a of the first welding wire 21 to be forward of the position b of the second welding wire 22 with respect to the direction of travel of the welding point on the outer surface 1a of the insertion port 1 (the direction opposite to the rotation direction R of the tube P).

In this way, the first welding wire 21 and the second welding wire 22 are used, and the first welding wire 21 is energized to generate an arc to form a molten part W on the outer surface 1a of the insertion port 1 as shown in FIG. 2. Before the molten part W hardens, the second welding wire 22 is applied to the molten part W in a non-energized state. As a result, a protrusion 10 that protrudes outwardly is formed on the outer surface 1a of the insertion port 1 by a weld buildup (weld bead). At this time, the second welding wire 22 is in a non-energized state, but is heated by being applied to the molten part W generated by the arc of the first welding wire 21, and the metal of the second welding wire 22 melts and is supplied to the molten part W as weld metal.

At the same time, the weld metal from the first welding wire 21 and the second welding wire 22 is fused with the base material of the insertion port 1 to form a penetration portion 11 at a depth of 10% or more and less than 80% of the thickness t0 of the base material of the insertion port 1 from the outer surface 1a of the insertion port 1. Here, it is more preferable that the ratio of the maximum depth t1 of the penetration portion 11 to the thickness t0 of the base material is 20% or more and less than 60%. If this depth ratio is too low, the strength of the protrusion 10 may be insufficient due to insufficient penetration, and if this depth ratio is too large, the base material may be penetrated. The inventors have discovered that the above-mentioned cold tandem welding method is optimal for setting such a depth ratio.

In other words, by using cold tandem welding when forming the protrusion 10 of the insertion port 1 by weld build-up, the amount of weld metal supplied per unit time increases, and the amount of melting per unit time (welding speed) can be increased. In addition, by attaching a non-current-carrying second welding wire 22 to the molten part W, the molten pool of metal material in the molten part W can be cooled, reducing the penetration depth and preventing dripping of the weld metal. As a result of these effects, it was possible to obtain the desired bead shape of the protrusion 10 at the same speed as with conventional welding methods using rings.

As shown by the dashed line in Figure 1, the completed shape of the protrusion 10 is a tapered surface 10c that gradually reduces in diameter toward the tip 1b of the insertion port 1 on the right side of the figure, sandwiching a flat cylindrical portion 10d in the center. In addition, a step 10b is formed between the rear end side and the outer surface 1a of the insertion port 1. As a result, the cross section of the protrusion 10 is trapezoidal in any cross section passing through the tube axis.

The shape of the protrusion 10 immediately after welding, as shown by the solid line in Figure 1, is a cross-sectional shape with a bead surface 12 that is slightly larger than the finished shape of the protrusion 10, so this is cut and shaped into the finished shape. In Figure 1, the tip 10a of the protrusion 10 coincides with the tip 1b of the insertion port 1, so the tube P is cut along the line indicated by the symbol S in the figure, but this cutting can be done according to the positional relationship between the tip 10a of the protrusion 10 and the tip 1b of the insertion port 1, and is not a required step. The shaping of the protrusion 10 into its finished shape can be done by combining a high-frequency grinder and lathe processing.

In FIG. 1, two-layer welding is performed to finish the entire circumference of the protrusion 10 during two rotations around the tube axis, so that the shape of the protrusion 10 immediately after welding has two peaks 12a, 12b on the bead surface 12. Similarly, the penetration portion 11 has two valleys 11a, 11b whose penetration depth is slightly deeper than the surroundings. By performing such two-layer welding or welding of three or more layers, the formation of the protrusion 10 becomes easier and more accurate. However, as shown in FIG. 4, it is also possible to perform one-layer welding to finish the entire circumference of the protrusion 10 during one rotation around the tube axis. In the case of one-layer welding, the shape of the protrusion 10 immediately after welding has one peak 12a on the bead surface 12 and one valley 11a whose penetration depth is slightly deeper than the surroundings in the penetration portion 11.

In the experiment, FeNi φ1.6 mm was used as the first welding wire 21 and the second welding wire 22, and the supply amount of the first welding wire 21 was 900 cm/min and the supply amount of the second welding wire 22 was 500 cm/min for a rotation speed of 25 mm/s on the circumferential surface of a tube P with a tube thickness of 6 mm, and good results were obtained by setting the weld metal amount to 160 g for the entire protrusion 10 in two-layer welding and securing a ratio of penetration depth to the tube thickness of about 33%. In addition, in one-layer welding, FeNi φ1.6 mm was also used, and the supply amount of the first welding wire 21 was 900 cm/min and the supply amount of the second welding wire 22 was 600 cm/min for a rotation speed of 12.5 mm/s on the circumferential surface of the tube P, and the weld metal amount was 170 g for the entire protrusion 10, and securing a ratio of penetration depth to the tube thickness of about 60%, and good results were obtained. In this regard, in the conventional method of forming the protrusion 10 using a ring, when using FeNi φ1.2 mm, the amount of weld metal for the entire protrusion 10 was 59 g when the rotation speed on the circumferential surface of the tube P was 25 mm/s and the supply rate of the welding wire was 920 cm/min. In other words, it can be understood that by using cold tandem welding in this invention, an increase in the amount of melting (welding speed) per unit time has been achieved.

In this embodiment, the tube P before the protrusion 10 of the insertion port 1 is formed is manufactured by centrifugal casting, but the manufacturing method of the tube P before the protrusion 10 is formed may be other than centrifugal casting, for example, a pouring casting method in which molten metal is poured into a mold by gravity and solidified. In addition, this invention can be applied to various tubes P as long as the insertion port 1 on which the protrusion 10 is formed is made of metal that is compatible with welding.

1 Insertion port 1a Outer surface 10 Protrusion 11 Penetration portion 20 Welding device 21 First welding material (first welding wire)
22 Second welding material (second welding wire)
P Tube

Claims (3)

A method for manufacturing a tube (P) having a protrusion (10) protruding radially outward from an insertion port (1) at one end in the tube axial direction, comprising the steps of:
The method for manufacturing a tube includes using a first welding material (21) and a second welding material (22), forming a molten portion (W) on the outer surface (1a) of the insertion hole (1) by an arc generated by passing an electric current through the first welding material (21), and applying the second welding material (22) to the molten portion (W) without passing an electric current through it before the molten portion (W) hardens, thereby forming the protrusion (10) by weld build-up. The method for manufacturing a tube body according to claim 1, in which a penetration portion (11) formed by fusing the weld metal of the first welding material (21) and the second welding material (22) with the base material of the insertion hole (1) is formed at a depth from the outer surface (1a) of the insertion hole (1) that is 10% or more and less than 80% of the wall thickness (t0) of the base material of the insertion hole (1). A tube body (P) manufactured by centrifugal casting, the tube body (P) having a protrusion (10) protruding radially outward from an insertion port (1) at one end in the tube axial direction,
a protrusion (10) made of weld metal provided in the insertion port (1) and protruding radially outward from an outer surface (1a) of the insertion port (1);
a penetration portion (11) located on the inner diameter side of the protrusion (10) and in which the base material of the insertion port (1) and the weld metal are fused together,
The penetration portion (11) extends from the outer surface (1a) of the insertion port (1) to a depth of 10% or more and less than 80% of the wall thickness (t0) of the base material of the insertion port (1);
The protrusion (10) is a pipe having a cylindrical portion (10d) formed on its outer surface so as to exert a function of preventing the earthquake-resistant pipe joint from coming loose.

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